Taxonomy• Taxonomy- the practice and science of

classification– Why do scientists classify organisms?• Used to organize living things into groups so that they

are easier to study• Helps identify the relationship between organisms• Helps to avoid confusion in naming and identifying

organisms

• Taxon- divisions with subdivisions; from the most specific taxon (species) to the most general (kingdom)

• Naming species– Species- group of organisms capable of interbreeding and

producing fertile offspring– Each species is identified by a binomial Latin name, which

refers to both the genus and species, with genus capitalized and species in lower case. The whole thing is italicized or underlined• Human = Homo sapiens• Great White Shark = Carcharodon carcharias• Megalodon Shark = Carcharadon megalodon

• Current classification system– Three Domains- all life dividing into 3

Domains1. Bacteria- single- celled microorganisms; they

are prokaryotes, which means they have no nucleus or organelles in their cells

2. Archaea- single celled microorganisms; also prokaryotes. When first discovered (1977), considered bacteria. After further research, they have no close relationship to bacteria

3. Eukarya- organism with eukaryotic cells (nucleus and other membrane bound organelles)

• 6 kingdoms1. Eubacteria- prokaryotes, unicellular; found in

every habitat on earth2. Archaebacteria- prokaryotes; unicellular; more

closely related to eukaryotes than bacteria; many species found in ocean

3. Protista- simple eukaryotes; either uni or multicellular without specialized tissues

4. Fungi- eukaryotes; unicellular and multicellular; heterotrophic decomposers

5. Plantae- eukaryotes; multicellular; cell walls; autotrophic photosynthesizers

6. Animalia- eukaryotes; multicellular; no cell walls; heterotrophic consumers

• How scientists classify organisms– Methods: organisms can be placed into certain

taxonomical groups based on their…• Morphology and anatomical structure• Biochemical structure (RNA, DNA, Protein sequences)

• How scientists classify organims– Phylogeny-evolutionary history of organism• Phylogenetics- study of evolutionary relatedness

among various groups of organisms, which is discovered through molecular sequencing data and morphological data• Phylogenetic tree- diagram showing the evolutionary

relationships among various biological species or other entities that are known to have a common ancestor